434 T. H. MORGAN AND C. B. BRIDGES 



RED 



Red heterozygous for eosin 



When a red female is mated to an eosin male the red-eyed 

 female offspring are heterozygous for eosin. The male has the 

 composition and color of the wild male. He is haploid for all 

 sex-linked characters and can be used as a standard for compari- 

 son with his sisters reared under the same conditions : 



Pi 



The eye color of these females heterozygous for eosin is the 

 same as that of their red-eyed brothers. No effect of the hetero- 

 zygous condition can be seen. 



Red heterozygous for white 



In former papers many records of such flies have appeared, 

 but to make a more critical examination we repeated the cross: 



Pi 



The eye color of the red females heterozygous for white was 

 like that of the wild stock females. 



